PRENATAL STRESS DEPRESSES IMMUNE FUNCTION IN RATS

The aim of the present study was to determine the effect of prenatal s tress on immune function in rats. Pregnant rats were stressed by noise and light, three times weekly throughout pregnancy. Experiments were performed on male and female offspring aged 2 months. Cellular immune responses of splenic lymphocytes to B-cell (pokeweed mitogen (PWM) and T-cell (phytohemagglutinin (PHA)) mitogens were measured by [H-3]thym idine uptake, and natural killer (NK) cell cytotoxicity in blood and s plenic lymphocytes was measured against the murine T-cell lymphoma, YA C-1, by a 4-h [Cr-51] release assay. Prenatal stress suppressed immune function as shown by a) decreased NK cytotoxicity in splenic and bloo d lymphocytes, indicating that the effect was not confined to a partic ular immune compartment, and b) decreased rate of proliferation of spl enic lymphocytes to PWM and a smaller depressant effect on their respo nse to PHA. The suppression of B-cell proliferation was more marked in the female and that of NK cell cytoxicity, in the male. Prenatal stre ss did not alter the distribution of subsets of lymphocytes, in either the spleen or blood, indicating that the reduction in proliferative a nd cytotoxic activity resulted from functional modifications of effect or mechanisms in the cells rather from alterations in their migration between immune compartments. The mechanisms underlying this effect of prenatal stress are not clear but could result from an action of mater nal stress hormones on the developing fetal neuroendocrine system. (C) 1998 Elsevier Science Inc.